Union Bank of India Amount deducted without informing

The balance in my account no was 5030 But amount of Rs. 2500 was deducted & I have received a message that available amount of Rs. 515 . 2500 h as been deducted in account without informing . which is not matching ( Message & Account Statement showing amount deducted ).

Kindly let me know why the amount has been deducted without informing.